Widely tunable continuous-wave Raman laser in diatomic hydrogen pumped by an external-cavity diode laser

What is to the authors’ knowledge the first experimental demonstration of a nonresonant cw Raman laser pumped by a tunable external-cavity diode laser (ECDL) is presented. The ECDL is phase-frequency locked to a high-finesse Raman laser cavity containing diatomic hydrogen $\left({\mathrm{H}}_2\right)$ by the Pound–Drever–Hall locking technique. The Stokes lasing threshold occurs at a pump power of $400\pm 30 \mathit{\mu }\mathrm{W}$, and a maximum photon conversion efficiency of $12.0\pm 1.3\%$ is achieved at 1.6 mW of pump power. A 40-nm tuning range of the cw Stokes emission, 1174–1214 nm, is obtained by tuning of the wavelength of the ECDL pump source.